Functional electrical stimulation (FES) systems have been developed using electronic body worn equipment which generates and delivers electrical impulses to the body to control muscle movement
Functional electrical stimulation (FES) systems are seen to have particular future application in providing persons suffering from spinal cord injury or deficiency, such as paraplegia, with a capacity to make controlled movements of their dysfunctional limbs.
Functional electrical stimulation systems use electronics to generate electrical impulses. These impulses are then delivered to the nerves or muscles of a subject via electrodes to stimulate movement of the muscles that are otherwise dysfunctional. In order for useful and controlled movements of limbs to be achieved several muscles must usually be operated in concert. This is normally achieved by an algorithm executed under the control of the FES system to deliver a pattern or sequence of stimulation impulses.
In implanted FES systems, the electrical impulses are transmitted from implanted stimulator units via electrically conducting leads to strategically positioned electrodes that deliver the electrical impulses directly to the nerves or muscles. The electrodes are typically positioned remote from the implanted stimulator unit and proximal to the nerves that direct movement of the associated limbs.
A common problem associated with a person losing controlled movement of their limbs is that the muscles that were previously routinely exercised are no longer functional and as such the muscles waste due to lack of exercise. In order to address the problem of muscle wastage, a number of exercise machines have been proposed which provide appropriate exercise to the muscles to prevent muscle wastage. Such machines are, however, typically designed specifically for such use and as a result the machines are generally expensive and cannot easily be adapted for use with alternative FES systems, such as implanted systems as opposed to surface stimulation systems. Also, exercising on a stationary bicycle is a typical critical step in adapting a person to the use of FES systems and as such easy access to such devices is highly desirable
Existing exercise bicycles and tricycles for use by paraplegics and the like essentially utilise sensors on the bicycle or tricycle itself, such as on the pedal crank, to initiate muscle stimulation. For example, U.S. Pat. No. 4,421,336 to Petrofsky describes a tricycle having a pedal position sensor mounted on the tricycle that senses the position of the pedal which then leads to the generation of stimulation signals applied to the legs of the subject.
Such systems use a computer to ascertain the position of the pedal and from this position the computer selects the muscles to be stimulated to continue the pedalling motion. The intensity of the stimulus is essentially dictated by the pedalling rate of the subject and the computer detects this rate by measuring the change in pedal position over a fixed unit of time. Unfortunately, such systems are complex and require the exercise bicycle to be dedicated to the specific purpose of providing stimulation to the invalid subject. Existing devices are not easily modified and it is not possible for a common exercise bicycle to be adapted to allow the subject to exercise in the absence of a dedicated machine. Further, existing machines rely upon the input from the bicycle to dictate which muscles are to be stimulated and at what intensity, thereby removing ultimate control of the movement from the subject.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention before the priority date of each claim of this application.